This invention concerns bimetals used as support members for shadow masks in color television tubes. Such bimetal support members are used to compensate for the thermal expansion of the shadow masks during operation. Examples of such compensators are shown in U.S. Pat. Nos. 3,330,980, 3,524,972, 3,524,973, 3,524,974, 3,700,948, 3,781,583, 3,823,336, 3,838,985, 4,285,106 and 4,645,120. This invention is particularly concerned with bimetal support members that are edge bonded, as shown in U.S. Pat. No. 3,700,948, instead of surface bonded, as shown in the other patents.
The edge bonded bimetal shown in U.S. Pat. No. 3,700,948 is a flat rectangular member and is used in smaller picture tubes. The high expansion alloy typically consisted of type 304 stainless steel, which is 18-20 Cr, 8-10 Ni, balance Fe. The low expansion alloy typically consisted of type 430 stainless steel, which is 14-18 Cr, balance Fe. Such a bimetal is not suitable in larger picture tubes, say, the 27" size. This invention discloses a bimetal support member suitable for use in such larger picture tubes.